1. Field of the Invention
The invention relates to aerospace propulsion. In particular, the present invention is directed to a liquid propellant rocket engine apparatus.
2. Description of the Prior Art
The aerospace industry is continuously looking for apparatuses and methods to reduce the cost of launching payloads into space. Presently, the typical launch cost for the injection of a payload into earth orbit is approximately ten thousand dollars per pound of payload. Most of the cost associated with this process is attributable to the large, complex, and expensive systems utilized to operate a launch vehicle.
Recently, there have been a number of attempts to reduce the cost per pound of payload through a combination of innovative vehicle designs and infrastructure developments. Unfortunately, although these efforts have been successful with regard to some areas, the cost per pound of payload continues to remain substantially unchanged. A primary reason for this lack of progress is the fact that most of the current efforts utilize liquid propellant rocket engine designs that are almost four decades old. Utilization of these vintage designs continues due the perceived high cost of developing and exploiting newer launch systems. In addition, cumulative increases in the reliability of these older rocket engine designs, coupled with a familiarity in their maintenance and operation, renders them among the currently preferred launch systems.
It has been noted that the performance characteristics of liquid propellant rocket engines improve as combustion chamber pressures are increased. In order to exploit the effects of increased chamber pressure, liquid propellant rocket engines are either tank pressurized or turbo-pump pressurized.
In a tank pressurized liquid propellant rocket engine, the propellant is pressurized in a main storage tank by either premixing of a small quantity of the propellants or by gas pressurization via the utilization of a chemically inert gas. The advantage of tank-pressurized systems is that is that they are relatively simple to construct. The disadvantage of tank-pressurized systems is that the propellant storage tanks must be designed to withstand extreme pressure and, as a result, are very heavy. This later fact results in a decrease in rocket vehicle performance with a commensurate increase in the cost per pound of payload.
In a turbo-pump pressurized liquid propellant rocket engine, a turbo-pump is employed to pressurize the propellants prior to their injection into the combustion chamber. To this end, measured quantities of propellants are chemically reacted and used to drive a turbine that spins a shaft and drives a centrifugal pump. The pump, in turn, pressurizes the propellants prior to their injection into the combustion chamber. The advantage of a turbo-pump system is that the main propellant storage tanks can be at a very low pressure and, thus, can have a lightweight configuration. The disadvantages of turbo-pump systems are that turbo-pumps are, typically, extremely heavy devices configured to generate and withstand high pressures. Further, turbo-pumps can be extremely complicated and expensive to build because they employ complicated blade geometries that must be cast using specialized techniques.
Recently, development has begun regarding a rocket engine employing as propellant liquid oxygen, commonly referred to as "LOX," and kerosene. These efforts utilize a rocket engine employing a completely ablative nozzle and combustion chamber. In operation, a single-shaft turbo-pump is employed to pressurize the propellants prior to their injection into the combustion chamber. The cost effectiveness of this new design is directly linked to the cost of the turbo-pump system. Thus, the current high cost of the proposed turbo-pump, i.e., in excess of one hundred thousand dollars, continues to limit the effectiveness of these systems in decreasing the cost per pound of injecting a payload into earth orbit or space.
A need exists for a reliable rocket engine apparatus that can be employed with a propellant including liquid oxygen and kerosene that is economical to manufacture and that does not suffer from the foregoing design and cost limitations.